Experimental and Numerical Framework for Study of Low Velocity Water Droplet Impact Dynamics

Impacting water droplets are capable of eroding soil, rock, turbine blades and even high speed aircraft. Research has shown that high velocity water droplet impingement onto a solid workpiece can strip paint, remove rust, and serve as a machining operation. This technique is different from waterjet cutting as a train of water droplets are used to transport momentum to a workpiece rather than a continuous jet. Also, no abrasive medium is used which produces an environmentally friendly process. The exploitation of this water droplet impact phenomenon in industrial applications as a means to deform and remove material does not currently exist. If the impact dynamics of water droplets can be understood and controlled, then industries would have the framework upon which they could employ this phenomenon in novel manufacturing equipment. In this paper, as a starting point, the impact force of 2.9mm diameter water droplets impacting at low velocities (∼2m/s) was studied experimentally and numerically. A piezoelectric force sensor was used to measure the transient force of impacting water droplets, while numerical simulations were used to identify the solid-fluid interaction and develop the basis for high velocity (>100m/s) liquid droplet impact dynamics. Agreement was established between experimental observations and numerical predictions for the impact velocities considered.